Chen B L, Baase W A, Schellman J A
Institute of Molecular Biology, University of Oregon, Eugene 97403-1229.
Biochemistry. 1989 Jan 24;28(2):691-9. doi: 10.1021/bi00428a042.
A disulfide-bridged variant of bacteriophage T4 lysozyme has been found to undergo a low- as well as high-temperature unfolding transition in guanidinium chloride [see Chen and Schellman (1989)]. The kinetics for this process have been followed for several temperatures, a range of guanidinium chloride concentrations, and a number of values of pH. Microscopic rate constants for protein unfolding and refolding were extracted from these data to explore the nature of the cold unfolding transition. The data were interpreted using transition-state theory. It was found that the Arrhenius energy is temperature dependent. The transition state is characterized by (1) a high energy and low entropy compared to the native state, (2) a heat capacity which is closer to the native state than to the unfolded state, and (3) a low exposure to solvent compared to the unfolded state, as judged by its interaction with guanidinium chloride. With increasing concentration of guanidinium chloride, the low-temperature unfolding rate increases strongly, and the refolding rate decreases very strongly.
已发现噬菌体T4溶菌酶的一种二硫键桥连变体在氯化胍中会经历低温以及高温的去折叠转变[见Chen和Schellman（1989年）]。在几个温度、一系列氯化胍浓度以及多个pH值条件下跟踪了该过程的动力学。从这些数据中提取了蛋白质去折叠和重折叠的微观速率常数，以探究冷去折叠转变的本质。使用过渡态理论对数据进行了解释。发现阿累尼乌斯能量与温度有关。过渡态的特征在于：（1）与天然态相比，能量高且熵低；（2）其热容与天然态更接近，而与去折叠态相差较大；（3）与去折叠态相比，与溶剂的接触较少，这是通过其与氯化胍的相互作用判断得出的。随着氯化胍浓度的增加，低温去折叠速率大幅增加，而重折叠速率大幅降低。
